[L. David Baron:]
>
> In http://lists.w3.org/Archives/Public/www-style/2012Mar/0013.html
> we agreed to accept my proposal in
> http://lists.w3.org/Archives/Public/www-style/2012Feb/1083.html for
> https://www.w3.org/Bugs/Public/show_bug.cgi?id=15838 : that is, we agreed
> that when transition-duration and transition-delay are both 0s that there
> should be no transition (and thus no events).
>
> However, we didn't agree whether that was the only case. I realized that
> there are a set of other cases where there probably shouldn't be a
> transition: in particular, when transition delay is as negative or more
> negative than transition duration is positive. In these cases the
> transition end event would have a firing time at or before the time the
> transition started, which suggests to me that maybe it shouldn't fire at
> all.
>
> Thus, I've written:
> # When the computed value of a property changes, implementations
> # must start transitions based on the relevant item (see the
> # definition of ‘transition-property’) in the computed value of
> # ‘transition-property’. Corresponding to this item there are
> # values of ‘transition-duration’ and ‘transition-delay’ (see the
> # rules on matching lists). Define the combined duration of the
> # transition as the sum of max(‘transition-duration’, ‘0s’) and
> # ‘transition-delay’. When the combined duration is greater than
> # ‘0s’, then a transition starts based on the values of
> # ‘transition-duration’, ‘transition-delay’, and
> # ‘transition-timing-function’; in other cases transitions do not
> # occur.
>
> Does this seem reasonable to others?
>
My apologies for catching this so late; I agree with the resolution and had
only one minor editorial question: is the "max(‘transition-duration’, ‘0s’)"
expression needed in this prose given that transition-duration explicitly maps
negative <time> values to 0s? Or is this just an editorial reminder to the reader?